The Two Companies Became the First Nonbank Financial Firms to Be Subject to New Rules

WASHINGTON—American International Group Inc. and General Electric Co. unit GE Capital Corp. could pose a risk to the U.S. economy if they were to falter, U.S. regulators said Tuesday in designating the two firms "systemically important."

The two companies became the first nonbank financial firms to be brought in for greater oversight, higher capital requirements and other new rules under a key provision of the 2010 Dodd-Frank financial law. They join a number of large banks and financial-market utility firms that...